1. Field of the Invention
The present invention relates to power supply module for a display device, and more particularly, to a method of switching capacitors in a power supply module of a display device and the related power supply module and display device.
2. Description of the Prior Art
In recent years, the thin film transistor (TFT) display has become the most popular display technology in the industry. A general TFT display includes a gate driver and a source driver for driving a plurality of transistors on the screen, so that the pixel corresponding to each of the transistors may appear various grey scales and brightness.
In the conventional TFT display, electric power of the drivers is supplied by a dedicated power supply circuit for the gate driver and the source driver, respectively, so that the gate driver and the source driver may output driving signals having different voltage levels. In general, most power supply circuits apply a DC-DC converter implemented by charge pumps to supply output power, and an external capacitor is incorporated to drive the operations of the gate driver and source driver. However, in order to reduce production costs and manufacturing time of the TFT display, the capacitors are implemented inside the integrated circuit (IC) to replace the external capacitor for several TFT displays.
The above DC-DC converters realized by the charge pumps require a large amount of capacitances to drive their output voltage. Since the capacitors are inside the IC, the magnitude of capacitance is easily limited by the area of the IC and thus fails to meet the requirements, especially when the resolution and size of the TFT display becomes increasing. This causes the requirements of capacitance quantity to increase as well, so that the problem of insufficient capacitance becomes more severe. Thus, there is a need to redesign the structure of power supply circuit and rearrange the method of applying the capacitors under the limit of capacitance quantity inside the IC, in order to enhance the efficiency of capacitor usage.